Energy consumption worldwide is generally increasing, and conventional hydrocarbon resources are being consumed. In an attempt to meet demand, the exploitation of unconventional resources may be desired. For example, highly viscous hydrocarbon resources, such as heavy oils, may be trapped in tar sands where their viscous nature does not permit conventional oil well production. Estimates are that trillions of barrels of oil reserves may be found in such tar sand formations.
To further increase hydrocarbon resource recovery efficiency, radio frequency (RF) energy may be used to provide heating. U.S. Patent Application Publication No. 2006/0180304 to Kasevich discloses a hydrocarbon recovery process whereby an RF antenna is positioned within a borehole. RF energy is supplied to the RF antenna to heat the hydrocarbon resources. The hydrocarbon resources are recovered from the borehole.
Fluids may also be injected into the borehole to increase hydrocarbon resource recovery efficiency. For example, nitrous oxide and carbon dioxide may be injected into the borehole.
Underground RF heating generally requires a device that can supply relatively large amounts of RF power to the antenna in the subterranean formation while maintaining fluid and/or gas control both in and out of the subterranean formation. U.S. Pat. No. 7,461,693 to Considine et al. discloses a wellhead assembly or interface that allows fluid or gas and RF to be communicated from above the subterranean formation to the wellbore within the subterranean formation.
Despite the existence of such a wellhead assembly, such systems may not be relatively reliable and robust. For example, such systems may not provide desired isolation and pressure control, while maintaining desired power levels. For example, it may be particularly desirable to maintain or control the coefficient of thermal expansion (CTE) growth, the temperature of the components, e.g., antennas, chokes, etc., and overall control of the well.